270 



AMERICAN SPIDERS AND THEIR SPINNINGWORK. 



hand were those cited above, and from Zululand and Surinam. But I 

 was able to pursue the matter by reference to locations given by a number 

 of naturalists. I was aided in this by references kindly sent me by Mr. 

 William Holden. Some of the localities thus obtained have been named 

 above, and others were found to correspond with the points represented 

 by the specimens examined. So far my conjecture was verified. 



The two lower arrow lines in the chart, C C and D D, give a general 

 view of the course and limits of the South Trades, which prevail in the 

 Atlantic Ocean between latitude 4 N. and 22 S., and the Pacific between 

 latitude 4 N. and 23 S. 1 It is, of course, understood that these limits 

 are not stationary, but follow the sun, moving northward from January 

 to June, and southward from July to December ; an oscillation which is 

 also indicated in the zone of distribution. They are, however, substantially 

 as above given, and may be compared with the following table, which 

 shows the southern geographical distribution of this species, according to 

 the authorities cited therein : 



TABLE OF DISTRIBUTION SOUTH OP THE EQUATOR. 



This table shows a distribution corresponding with the limits of the 

 South Trades, with, in three cases, viz., Sidney (3), Surinam (14), and Val- 

 paraiso (15), a slight oscillation in accord with a fact above stated. Thus 



1 The arrow line which indicates the course of the Trades is intended to give only the 

 general direction. In point of fact, however, that course, in the case of the Southern Trades, 

 is more nearly conterminous with the line of distribution than here shown. The arrow 

 line should not run directly westward from Valparaiso,- Chili (No. 15), but from a point 10 

 above it, passing just south of Friendly Isles (No. 19). 



2 Gerstaecker speaks of species as distributed over a large part of Africa, Asia, and South 

 America. See Von der Decken's Travels in East Africa, III., ii., page 482. 



